Increases in glomerular cellularity and accumulation of extracellular matrix material are prominent histologic findings in a number of clinical and experimental glomerular diseases. Transforming growth factor-beta (TGF-beta) has been identified as a potentially important modulator of glomerular pathology based on its demonstrated ability to regulate proliferation and extracellular matrix synthesis by cultured glomerular cells. In addition, we previously found that normal rat glomeruli contain high concentrations of TGF-beta1 and TGF-beta2 and that glomeruli possess unique TGF-beta binding proteins or receptors. The goal of these studies is to better understand the actions and mechanisms of action of TGF-beta in the glomerulus. The current focus of these studies is on the TGF-beta binding proteins and/or receptors which are present in glomeruli.